THURSDAY, Dec. 21, 2017 (HealthDay News) -- Cancerdrugs have become so pricey that U.S. patients often can't afford them, a new study finds.

The findings suggest that high out-of-pocket costs may be a barrier to potentially life-saving or life-prolonging treatments, the researchers said, and raise questions about whether patients will be able to take advantage of new cancer treatments.

"Imagine leaving your doctor's office with a plan, ready to start treatment, only to find you can't afford it," said study author Jalpa Doshi, from the University of Pennsylvania School of Medicine.

"It adds more stress at what is already a stressful and scary time," she said in a UPenn news release. Doshi is a professor of general internal medicine at Penn and director of value-based insurance design initiatives at the university's Center for Health Incentives and Behavioral Economics.

The study involved more than 38,000 patients with a new cancer diagnosis or a change in their disease that required a new treatment, Doshi said. The patients had different types of insurance, including Medicare. From 2014 to 2015, all of them had received a new prescription for one of 38 types of cancer drugs.

Among those whose out-of-pocket cost for a prescription was less than $10, about 10 percent did not fill their prescription, the study found. However, the rate rose to 32 percent when people had to pay $100 to $500 out-of-pocket, and to nearly 50 percent if the out-of-pocket cost was more than $2,000.

The type of cancer made essentially no difference in whether patients picked up their prescriptions -- even when treatment with the prescribed drug might have extended their life, according to the researchers.

The study also found that few of the cancer patients went on to use another cancer medication in the same drug class in subsequent months, including intravenous therapies.

When patients with higher out-of-pocket costs did fill their prescriptions, they were more likely to delay doing so than were those who faced lower costs, the findings showed.

The study "shows the importance of discussing financial barriers up front, during conversations about treatment options, even with patients who don't raise concerns," Doshi said. "Patients may not be aware of how expensive their prescriptions will be, and physicians may not realize that a patient has opted not to fill the prescription."

When the study was done, one in eight patients had out-of-pocket costs higher than $2,000, but that number has increased since the study was conducted, according to the researchers.